SOI message 1st December 1999
The average SOI over the previous 30 days has risen to +12.2 . Based on the SOI, the probabilities of exceeding median rainfall during the total period from December to February range predominantly between 50 - 70% in much of the eastern States, rising to 80% in some coastal Queensland and NSW districts.
Review of Climatic Forecasts and Information
Based on the latest values and trends of the SOI, the probabilities of exceeding median rainfall during the total December-February period are around 50% in much of the eastern States of Australia. However, along the Queensland coast (up to 400 kms inland), and coastal and inland areas of NSW they are mainly 60-80%.
Sea-surface temperatures in the Pacific Ocean indicate a weak La Nina pattern. According to the Bureau of Meteorology Research Centre (BMRC) temperatures in waters off the Australian coastline have increased considerably during Aug-Oct; they are now mostly above average except in Queensland where they are mainly normal. Most experimental models are suggesting that neutral conditions will predominate by about April.
The most recent forecast from the Bureau of Meteorology, released on 11November, indicates that for much of New South Wales, south-east Queensland and Western Australia, there is a 60% to 75% chance that rainfall will exceed the median during the total December-February period. This outlook is based on sea-surface temperature patterns; currently probabilities are boosted by temperatures in the Indian Ocean off Western Australia being warmer than normal.
The likelihood of above-median pasture growth in October to December (during a 'neutral' SOI year) varies little from the 'all years' average values. Providing rainfall is at least average over that period, prospects for above-average pasture growth are high in areas where pasture condition is good (i.e. high perennial grass basal cover).
The next passage of the 30- to 50-Day Oscillation is expected in the last week of December.
It is important to obtain more detailed information for your location. This can be obtained from the Australian Rainman software package. Also a lot of additional information is available on our FarmFax system, our Internet World Wide Web service called 'The Long Paddock', and on BoM's Fax and internet information services.